The present invention relates to a novel microorganism capable of oxidizing manganese; to a microbial symbiont of algae and one or more microorganisms chosen from the genus Cedecea bacterium GSJ/MITA24A/ASHO-RO/1, the genus Aeromonas bacterium GSJ/MITA24B/ASHO-RO/2, and the genus Shewanella bacterium GSJ/MITA24C/ASHO-RO/3; to a method for culturing the microbial symbiont in a solution of artificial seawater (Kester) diluted with water; to a method for removing manganese from water containing manganese using the symbiont; and to a method for using the recovered manganese.
Various methods for removing heavy metals, particularly manganese, from water containing them are known. Among them, a chemical treatment for the removal of manganese comprises adjusting water containing manganese ions to a strong alkalinity of pH 10 or more to precipitate manganese dioxide, separating and removing the resulting manganese dioxide from the water, then neutralizing and discharging the manganese-free water. A microbial method for the removal of manganese requires the addition of a large amount of organic matter as nutrients. In addition, it often utilizes only microorganisms capable of removing manganese, obtained through their separation and purification, and so the microorganisms may lose their ability to remove manganese during the subculture and storage of them. Any of these methods cannot satisfy demands on costs and removal performance. Therefore, development of low-cost and effective methods for removing manganese from water has been expected.
Under these circumstances, objects of the present invention are to find the existence of a novel microorganism and a microbial symbiont thereof both having an ability to efficiently remove heavy metals, particularly manganese, and to provide the novel microorganism, the microbial symbiont, a method for culturing the microbial symbiont, a method for removing manganese from water containing manganese, and a method for recycling manganese recovered.
The present inventors have achieved the present invention by finding the fact that in water a particular microbial symbiont has an ability to capture heavy metals, particularly solid manganese, and an ability to oxidize dissolved manganese so as to precipitate it. The present invention is as follows.
(1) A microbial symbiont of manganese oxidizing bacterium and algae.
(2) A microbial symbiont as described in (1), said algae comprises one or more algae chosen from blue-green algae (cyanobacteria) such as Oscillatoria; diatoms such as Navicula; and green algae such as Ulothrix.
(3) A microbial symbiont as described in (1) or (2), said manganese oxidizing bacterium comprises one or more bacteria chosen from the genus Cedecea bacterium GSJ/MITA24A/ASHO-RO/1, the genus Aeromonas bacterium GSJ/MITA24B/ASHO-RO/2, and the genus Shewanella bacterium GSJ/MITA24C/ASHO-RO/3.
(4) The genus Cedecea bacterium GSJ/MITA24A/ASHO-RO/1 capable of oxidizing manganese.
(5) The genus Shewanella bacterium GSJ/MITA24C/ASHO-RO/3 capable of oxidizing manganese.
(6) A method for culturing a manganese oxidizing bacterium, wherein the culture is conducted in a solution of artificial seawater (Kester) diluted with water supplemented with organic nutrients.
(7) A method for culturing microbial symbiont as described in (1) or (2), wherein the method comprises culturing the symbiont in a solution of artificial seawater (Kester) diluted with water in the presence of a sludge of manganese mineral deposit and in the absence of organic matter.
(8) A method as described in (6) or (7), wherein 0.5- to 20-fold dilution of artificial seawater (Rester) is used.
(9) A method, as described in (8), wherein the microorganism is grown at a pH of 5 to 8 only with sunlight.
(10) A method for treating water containing manganese, wherein the method comprises contacting the water containing manganese with a manganese oxidizing bacterium to oxidize and precipitate the manganese, thereby removing the manganese from the water.
(11) A method for treating water containing manganese, wherein the method comprises contacting the water containing manganese with a microbial symbiont of manganese oxidizing bacterium and algae to oxidize and precipitate the manganese, thereby removing the manganese from the water.
(12) A method as described in (10) or (11), wherein said manganese oxidizing bacterium comprises one or more bacteria chosen from the genus Cedecea bacterium GSJ/MIT24A/ASHO-RO/1, the genus Aeromonas bacterium GSJ/MITA24B/ASHO-RO/2, the genus Shewanella bacterium GSJ/MITA24C/ASHO-RO/3.
(13) A method for recycling the recovered manganese as described in (10) or (11), wherein the method comprises recycling the recovered manganese as a material for manufacturing products such as dry cells, glazes, iron, glasses.